class Queue {
	constructor() {
		this.items = []
	}
	enquene(val) {
		this.items.push(val)
	}
	dequene() {
		return this.items.shift()
	}
	front() {
		return this.items[0]
	}
	isEnpty() {
		return this.items.length === 0
	}
	size() {
		return this.items.length
	}
	toString() {
		return this.items.join('').replace(/,/, '')
	}
}
